Robbie Williams disappeared from view at the end of 2006. Since then, he has become obsessed with UFOs and extraterrestrials. To gather evidence, he and Jon Ronson headed deep into the Nevada desert.

On December 18 2006, Robbie Williams played the last of 59 stadium shows in a row, announced he was going to spend Christmas at his home in Los Angeles, and then basically disappeared. He was hardly seen at all in 2007. He briefly checked into rehab. He spent quite a bit of time hiking and playing football (he owns a football pitch on Mulholland Drive). Then he stopped hiking and playing football. His record company, EMI, announced he had no plans to release an album in 2008. Today he unexpectedly calls me to ask if I want to go with him to the desert in Nevada to meet UFO abductees.

"I've been spending so much time at home on the internet on sites like AboveTopSecret.com," he says. "I want to do something. I want to go out there and meet these people. I want to be a part of this. I want to do something other than sit in my bed and watch the news. And it starts with the UFO conference in Laughlin, Nevada, on Thursday. We can hear people's testimony about being abducted by aliens. There's an entire family of abductees going to be there, apparently."I log on to the conference website. It's taking place at the quite down at heel-looking Aquarius hotel and casino. The conference slogan is Educating The World One Person At A Time, which makes it sound as if there won't be many people attending. The speakers will include Ann Andrews, from Lincolnshire, who claims her son Jason has had "disturbing experiences at the hands of many different alien species", and a surgeon, Dr Roger Leir, who claims he has extracted from patients 15 metallic implants that are not of earthly metal."I wonder if he'll bring the implants along," I say."So you can see with your own eyes whether they're earthly or not?" Robbie asks."Yes," I say."According to Jon," Robbie says.He seems a bit disapproving of my scepticism. I tell him that my problem with spaceships is this: if they exist, why do they reveal themselves to the human race only in ambiguous ways? "I think maybe they're making mistakes," he replies. "I think the shield comes off by mistake and they were there all the time." He pauses. "I don't want to hear any debunking because I want to believe."I fly to Los Angeles. When Robbie comes to his door, I hardly recognise him. He has grown a very bushy beard. He sees me scrutinising it, slightly agape, and says, "OK, I'm piecing it together now. I've grown a beard and I'm going to Nevada to speak to people about UFOs. I think I should shave so I don't look so mad."Actually, I don't think his beard is a visual symbol of any kind of madness. This is just the first time in 18 years he has taken a break from work and is enjoying doing things he was never before allowed to do, which includes having a beard."Pop stars aren't allowed to have beards," he says. "Name me a pop star with a beard.""Biffy Clyro," I say."I'm talking about pop stars," Robbie says.We go to his TV room. His girlfriend, the actor Ayda Field, is in there, watching a UFO DVD. We all watch it. This isn't all he does nowadays - he has been writing songs and playing golf, too - but the paranormal has become a very big part of his life since he disappeared from public view.Robbie first contacted me in 2005. He telephoned me out of the blue from a hotel in Blackpool where he was filming the video for Advertising Space. He said he liked a book I had written about conspiracy theorists and was thinking of spending a night in a haunted house."Do you know any?" he asked."I'll make some inquiries if you like," I said.I spent a week sending emails: "Dear Lady X, I've read that, if the portrait in your drawing room is moved, a ghost is apparently disturbed and manifests itself. The pop star Robbie Williams would like to spend a night in a haunted house and so I wonder whether he and I can pay a private visit."I expected not to hear back from anybody but, in fact, once I invoked Williams' name, owners of country piles started flinging their ghosts at me as if they were their debutante daughters."One of the guest bedrooms is definitely haunted by a young woman called Abigail who was starved to death by a monk in 1732," emailed one baroness. "Robbie is more than welcome to spend the night."I was surprised to find how widespread the belief in ghosts was among the aristocracy. Every person I contacted responded instantly to say their houses were definitely haunted and Robbie was more than welcome to spend the night. But it never happened. He cancelled because of his workload; he had to fly around the world to promote his album, Intensive Care. But we kept in touch. He'd speak wistfully about some future day when he'd have less work on and could investigate the paranormal for real. And now that day has come.Laughlin, Nevada, looks from the sky like a tiny, ugly Las Vegas, a cluster of crumbling themed casinos poking strangely out of an expanse of desert. We are travelling here in a private plane that Robbie has rented for the day. He has brought along Ayda and a lugubrious friend, Brandon. Being on a private plane is exciting. The flight attendant says Snoop Dogg often uses this plane and we can do anything we like. Robbie and his friends look at each other. The truth is, everyone is getting a bit older. Everyone here is nice and polite and quite genteel, and so, instead of doing "anything", we spend the journey eating breakfast rolls and talking about how exciting it is to be on a private plane."The toilet is amazing," I say."Am I allowed to stand as we land?" Brandon asks."We're on a private plane going to Nevada to hear abductees speak about their experiences," Robbie says. "That's ace."We land. A car is waiting on the Tarmac to take us to the nearby Aquarius hotel. We take the escalator to the second floor, walk past the stalls selling Secret Space: What Is Nasa Hiding? DVDs, past a giant inflatable alien, and into the cavernous conference room where British speaker Ann Andrews has just begun her audiovisual presentation to an audience of 500.I have to say, after all the anticipation, she seems a bit boring to me. She's recounting various tales of alien visitations in quite a dull voice. I half switch off and glance over at Robbie. He is engrossed. He is leaning forward, taking in every word, rapt. I decide to pay more attention so I can try to understand why.Ann Andrews' life was quite ordinary, she says, until 1984, the year her son, Jason, was born. She flashes on to the screen a snapshot of a sweet little boy sitting in a field in Lincolnshire with a horse in the background."That's Jason," she says.One day, when Jason was a toddler, Ann says she noticed he had a terrified look on his face. She asked what was wrong. He replied that aliens had appeared the night before at the foot of his bed and taken him to their spaceship, where they conducted tests on him. He said it was happening every night. As the weeks and months passed, Jason's story apparently never changed. When nobody was looking, aliens would come, float him up to a spaceship, and teach him the mysteries of the universe. They would teach him that he was placed on earth to become a psychic sage."We took him to a psychiatrist," Ann says. "We cried so much. We had him tested. But the tests all came back negative."And then one day when Jason was 12, Ann says she made a very big decision. She decided to take the giant leap and believe her son. Every word. She has subsequently written a series of books about Jason including one called Jason, My Indigo Child: Raising A Multidimensional Star Child In A Changing World.I lean over to Robbie."She believes Jason!" I whisper. "She believes it all! Isn't that amazing?""What's the other side of that, though?" Robbie whispers back. "It's either believe everything the boy is saying or remain steadfast to earthly beliefs and have a black sheep in the family. 'Oh, it's him again.' For her own sanity she has had to believe him." He pauses. "But for me, right now," he says, "everything she's saying is true."Ann's audiovisual address ends with her projecting on to the screen behind her a series of extremely blurry photographs. From time to time, she says, Jason is summoned to the spaceship for some psychic brush-up training. When this happens, Ann tries to photograph the UFOs. But she has only a disposable camera and so the pictures always come out fuzzy and inconclusive.It's time for the Q&A. Unexpectedly, Robbie's friend Brandon stands up and walks to the front. Brandon is a record producer and co-wrote some of the songs on Robbie's last album, Rudebox."I just wanted to ask, why don't you buy a better camera?" he says. A slight gasp reverberates around the hall. People don't usually ask cynical questions at UFO conferences."I'm absolutely useless at anything technological," Ann replies."Have you ever had any psychiatric evaluation or presented yourself for that?" Brandon asks. Robbie flinches and smiles."No, I haven't," Ann says. "I'd like to think I'm all there, but if I'm not, there are quite a few of us that have these experiences, so maybe we're all crazy!" She laughs, awkwardly."Thank you very much," Brandon says.Robbie goes out for a cigarette. I tell Brandon I'm surprised Robbie brought him along after what he'd said about not wanting to hear any debunking."There's two sides to Rob in that respect, though, aren't there?" Brandon says. "There's the side that wants to go along with it, but there's also a very sarcastic, sceptical side." He pauses. "Which I'd like to think is the real side." Robbie comes back."My toes curled up the moment you walked towards the stage," he tells Brandon. "But I think questioning somebody's sanity when this is happening to them is perfectly acceptable. I question my own."We're standing near the table where Ann is signing copies of her various books about Jason."She reminds me of my mother," Robbie says, glancing at her. "Mum was a tarot card reader. She'd have people round and read their palms. She'd talk about spirits and ghosts. On the shelf of books just outside her room, there'd be the books about the world's mysteries, elves, demons, witchcraft. I was so scared. I'd never talk to her about it. Instead, I just lived in fear of all of this stuff. Maybe that's why I want to investigate UFOs and ghosts and everything. So I can work out why I get scared at night." He pauses. "I'll go and say hello to her."He approaches the table. "Hi, darling," he says, "I'm Rob. Can I buy a book from you? Will you sign it for me? How is Jason these days? Is he happy? Has he got many friends?""No," Ann says, "Jason doesn't have many friends at all. In fact, it's been awful, really. He's socially shunned.""When did this social shunning begin?" Robbie asks. "What age?""I suppose it was when my first book about him came out," Ann replies, "when he was 14. He lost all his friends at school. Nobody wanted to know him. And, of course, word got around the small village where we live. It got very nasty.""I can completely relate to that," Robbie says. "What is it he encounters from people?""In England, in particular, people are really spiteful," Ann says. "They ridicule him. They call out things from across the road like, 'Oi! Mental boy!' "Robbie puts his hand on Ann's hand."Even if this was all made up, which I don't believe, by the way. Even if it was," Robbie says, "compassion should be shown anyway. Well, thank you." Robbie pays for the book and goes to leave."You know," says Ann, "you look very much like Robbie Williams." There's a silence. It's as if Robbie was having so much fun, he briefly forgot who he is."I am Robbie Williams," he says."Can I just say I'm a big fan of yours?" she says."Oh, bless you. Thanks, darling," he says. "And please send Jason my best. Maybe we can have a chat one day. In fact..." Robbie writes out his email address for Ann. "Tell him to drop me a line if he wants. It must have been a terrible time for you, and an awful time for him. It's just so sad to hear it happens. It's happened to me.""Really?" Ann says."I think joining Take That was like leaving on a spaceship," Robbie says, "and coming back and all your friends going, 'He's weird now.'"We queue for the lunch buffet at the restaurant."I'm glad I had a chance to sit down with her and talk to her, so I could see her eyes and read her," Robbie says. "She's a really beautiful woman.""It's interesting that you identified with Jason," I say."But that's not what I want to talk about," Robbie says. "Because it's long-winded, and whingeing, and nobody wants to hear a whinger." He pauses. "But if I was doing your job I'd be asking that, because I'm asking the same question of myself, about why that nearly moved me to tears."He signs a few autographs, and then a few more, and then everyone starts asking for his autograph, including one elderly American who says, "I don't know who you are but my daughter works for MTV and so she might." Word has obviously got around the conference that, in the absence of any aliens, the most interesting thing to have come down from the sky today is Robbie Williams. One conference organiser asks him if he'll consider being their official spokesperson."We need someone like you to spread the word and get the young people in," he says. Robbie seems quite attracted by the offer."This is possibly the most important thing ever to happen to the planet," he says. "It just amazes me that people aren't as interested as I am in this stuff."There is so much commotion, we miss much of the next presentation and consequently never find out "what happened when four artists embarked in 1976 on what was expected to be a routine fishing trip".This isn't the first time that Robbie's fame has hindered his forays into the paranormal world. A few years ago he invited the TV psychic Derek Acorah to his home for a psychic reading. A story subsequently appeared in the Sun under the headline, I Helped Robbie Williams Talk To His Dead Gran:"Robbie invited me to his apartment in London. We chatted and he told me how much he loved the programme [Living TV's Most Haunted]. He said he had given Most Haunted DVDs to lots of friends, including Robert De Niro, Danny DeVito and Billy Crystal, and they were hooked. I was able to contact a couple of his loved ones, including his grandmother, whom he dearly loved. It was very emotional.""The twat used my dead nan to sell his DVD!" Robbie told me, quite furiously, at the time. "Plus, I've never met Robert De Niro, Danny DeVito and Billy Crystal. I've never even met them!"Robbie never spoke to Acorah again, but he persevered with psychics for a while. He met one he liked a lot more, but then one night over dinner the man told Robbie that he wasn't only a leading psychic, he was also "one of only eight people outside Japan ever to be awarded a samuraiship". He said if anything were to happen in Japan, he would have to drop his psychic career "and fly over there to protect the emperor". After dinner Robbie did a bit of research and discovered that nobody has been awarded a samuraiship since 1872 and that "samuraiship" isn't even a real word."Haven't all those bad experiences with psychics shaken your wider faith in the paranormal?""I suppose they have," he says. "I never watch psychic TV shows any more." He shrugs. "And I suppose it might happen with UFOs, too. And then I might be able to get on with my life."But if that day ever comes, it's not going to be today, for at this moment an intriguing rumour reaches us. Apparently, a woman tells Ayda, a number of conference attendees spotted a battle between two giant reptilian beings in the desert outside the hotel the other night ."Did anyone take any photographs of the battle?" Ayda asks her."No," she says, "but someone collected a tissue sample and gave it to Dr Roger Leir. He might show it to you, if you can find him."Robbie says he'd recognise Dr Leir if he saw him. He has been a talking head on UFO documentaries Robbie has watched. And, sure enough, he spots him in the coffee shop adjacent to the casino. Robbie says he feels starstruck around UFO experts in the way other people feel starstruck around pop stars."Doctor," he says, "sorry, I'm Robbie. I saw you at the Conscious Life Expo. And I've seen you many times on the Discovery Channel.""I've been a lot of places," Dr Leir growls."We've heard that you have a reptilian tissue sample here in the hotel," I say."Have you done any tests on it?" Robbie asks."I only got it yesterday," Dr Leir says."Can we see it?" I ask."Sure," he replies.He takes us to his room. Dr Leir is the surgeon who claims to have extracted from patients 15 implants that are not of earthly metal. In the lift I ask if he has brought any of the implants to the hotel. He looks at me as if I'm an idiot."That would be absolutely ludicrous, unscientific and ridiculous," he barks. "I keep them locked away." We reach his bedroom."Where's the skin stored?" Robbie asks. There is a silence.He produces it from his wardrobe. It is a tiny flake at the bottom of a jar. Robbie, Ayda and I crowd around and examine it."It could be a scale," I say. "It could be a reptilian scale - which is, of course, the hope - or it could be a little bit of a wing of a moth. Could it be a moth wing?""It could be a lot of things," Robbie says, cutting me off. "So, Dr Leir, this was given to you last night. Are you excited about what it may be?""In a word," Dr Leir replies, "no.""Oh," Robbie says."It could be a piece of nothing," snaps Dr Leir. "I was recently sent an object that was surgically removed from an abductee. I put it under the electron microscope. It looked like an organic compound, so we went to the next level. We did a test that uses infrared spectroscopy. Long story short, it was a piece of wood.""Ah," says Robbie, a bit disappointed."So I just spent $25,000 to look at a piece of wood," Dr Leir says. "You ask me if I get excited? No."We fall into a slightly depressed silence."Do you worry that the aliens might want their stuff back?" Robbie asks, hopefully. "Do you get scared that they may want to come and get their transmitters back?""Well, if they want them back," Dr Leir says, "they certainly have an advanced technology over what we have. They could just take them."And so ends our day at the conference. Robbie buys 15 UFO DVDs and we catch the plane back to Los Angeles. He puts the pile on the table in his TV room. They have titles such as UFO Space Anomalies: 1999-2006. I ask if he's really going to watch them all. He nods."I used to read the Sun, the Mirror, the Mail all the time," he says. "Eventually I had to stop looking because I'd find things that would upset me, whether it would be about me or about somebody else. So I had to fill that void. And that void has been filled with this stuff."I think it's healthy that he doesn't look himself up in the papers any more. That week alone it had been falsely reported in the News Of The World that he had been dumped by a "Norwegian beauty" called Natassia Scarlet Malthe, and falsely reported in the Daily Star that he had been having secret face-to-face meetings with "mental conspiracy theorist David Icke" (they've never met). But the world he's obsessed with now - the UFO world - has its many liars, too."It's surely out of the frying pan and into the fire, liar-wise," I say.Robbie nods. He says he knows that there is a chance it's all nonsense. "But even if it is all made up," he says, "it's better made-up stuff than what the tabloids are writing. It's more interesting. To me, anyway.""And it isn't about you.""Yes," Robbie says.I leave him standing on his balcony with Ayda, and he does seem happy, gazing up at the sky, even if there's nothing paranormal up there."There's always this weird black circle," Ayda says. "You see that black patch over there? It's like dark fog.""Yeah," Robbie says, "but that might be something as easily explained as light pollution." He pauses. "Right now I'm, 'You crazy American bitch! That's just light pollution!' But if we didn't have company, I'd be going, 'Let's stare at it for an hour and a half. Materialise! Materialise!' We'd be doing our materialise dance. But let's not do that while Jon's here. He'll think I'm weird." They carry on looking at the night sky."No," Robbie says, finally, "I don't think there's anything up there tonight."• A radio documentary of their trip, Robbie Williams And Jon Ronson Journey To The Other Side, will be on Radio 4, May 6, at 6.30pm.